Don't skip the water conditioner or assume your tap water is fine just because it looks clear. Chlorine and chloramine will wreck your fish and kill beneficial bacteria in your tank, so treating tap water isn't optional - it's basic tank maintenance. Seachem Prime is a solid choice and does work; it binds chlorine and chloramine instantly so they can't harm anything. With high chlorine levels in your water report, you're actually doing exactly what you need to do.
The conditioner won't be wasted money. Beyond neutralizing chlorine, Prime also detoxifies heavy metals that might be in your tap water, which adds an extra layer of protection. You're using it correctly - just dose it according to the bottle before adding water to the tank. For a 30-gallon setup with regular water changes (sounds like you've got a new tank, so you're probably doing them weekly or every other week), a bottle lasts a while.
Water changes themselves don't need to be fancy. Just treat the water you're adding the same way you did at setup, let it reach roughly the same temperature as your tank water so you don't shock the fish, and add it in. Some people overthink it, but consistency matters more than perfection. Since you've got high chlorine anyway, keeping up with the conditioner is way cheaper and easier than dealing with a crashed tank later.